The invention relates to certain aspects of a regenerator in a catalytic cracking unit. In other aspects, the invention relates to regenerating a cracking catalyst.
Cracking catalyst is regenerated by burning off the coke deposits which were laid down during the previous cracking cycle. The coke burn-off usually occurs in a fluidized bed in the presence of air optionally containing steam. The air is distributed into the bed through hundreds of nozzles connected to a piping system. When the nozzles fail, catalyst is drawn into the air piping, cutting the pipes from the inside. The ability to distribute the air throughout the bed is lost. Catalyst can no longer be regenerated properly. Unit product value -falls until the unit must be shut down to repair. Damage could be very extensive due to uncontrolled discharge of air from eroded piping.